Hot rolled strip cooling device with coolant header

ABSTRACT

The present invention discloses a coolant header for hot rolled strip cooling devices, which cools a hot rolled strip fed from a finish rolling mill. The header includes a body provided with a plurality of discharging holes formed through the lower surface of the body such that the discharging holes are arranged along the width of the hot rolled strip and at least three rows of discharging holes are arranged along the length of the hot rolled strip; a coolant pipe provided in the coolant header, with an outlet hole formed on a side surface of the coolant pipe to discharge coolant; an inclined plate placed in front of the outlet hole of the coolant pipe such that the plate is inclined downwards, thus evenly distributing the coolant discharged from the outlet hole over the entire surface of the coolant header; a perforated plate placed above the discharging holes and causing the coolant to flow uniformly; and a flow stabilizing filter placed between the discharging holes and the perforated plate and causing the coolant to flow in a stabilized laminar manner. The present invention discharges a great amount of stabilized flow coolant onto the hot rolled strip, thus maximizing the strip cooling efficiency.

TECHNICAL FIELD

The present invention relates, in general, to coolant headers todischarge coolant and, more particularly, to a coolant header for hotrolled strip cooling devices, which can maximize the hot rolled stripcooling efficiency.

BACKGROUND ART

Hot rolled strips, which are sequentially fed from a hot strip mill, arecooled while passing over a run-out table of the mill. In the abovestate, the process for cooling the hot rolled strips has typically beenexecuted by spraying coolant from nozzles of a coolant header onto a hotrolled strip. Conventional coolant headers, which spray coolant onto hotrolled strips from nozzles, have been classified into turbulentflow-type headers, spray-type headers and laminar flow-type headersaccording to the coolant spraying style.

The turbulent flow-type coolant headers are configured such that highpressure is applied to the interior of a coolant header and coolant issprayed onto a hot rolled strip. Thus, the turbulent flow-type headersnecessarily have new devices to produce high pressure, thus havingcomplex construction and increasing installation costs. Furthermore, thevelocity of coolant sprayed from nozzles of the turbulent flow-typecoolant header is very high, so that the flow of coolant which issprayed from the nozzles and cools the hot rolled strips is unstable.Thus, when the turbulent flow-type coolant headers are used to cool hotrolled strips, large temperature deviations may be induced in each ofthe strips along the width of the strip.

On the contrary, the spray-type coolant headers to spray coolant throughnozzles having small diameters may evenly spray coolant over the overallsurface area of each hot rolled strip. However, the spray-type coolantheaders are problematic in that the flow rate of coolant sprayed from aheader per unit time is not too enough at normal pressure condition, sothat the header cannot quickly cool the hot rolled strips and,furthermore, the strip cooling efficiency is reduced. Thus, it is noteasy for the spray-type coolant headers to control the temperature ofthe strips while cooling the strips.

The laminar flow-type coolant headers solve the problems of the twoabove-mentioned types of coolant headers by discharging relativelystabilized coolant and by evenly cooling the hot rolled strips along thewidth of each strip.

FIG. 1 illustrates a sectional area of a conventional laminar flow-typecoolant header having the above-mentioned properties.

As shown in FIG. 1, the conventional laminar flow-type coolant headercomprises an outer tub 10 to store coolant therein, two inner tubs 20 toguide the coolant current discharged from the header onto the surface ofa hot rolled strip, and a coolant supply pipe 30 to supply the coolantto the outer tub 10. In the coolant header, both the inner tubs 20 andthe coolant supply pipe 30 are arranged along the width of the hotrolled strip.

The coolant supply pipe 30 is arranged between the two inner tubs 20which are arranged in two lines, with two coolant outlet holes 31 formedon an end of the coolant supply pipe 30 so as to supply the coolant tothe respective inner tubs 20. However, when the coolant discharged fromthe outlet holes 31 is directly introduced into the inner tubs 20, thecoolant may flow undesirably quickly and become unstable. Thus, to allowthe outlet coolant to flow stably, the outlet holes 31 are placed lowerthan the inlet holes of the inner tubs 20. Furthermore, to cause thecoolant to reliably flow in the laminar flow pattern, both a perforatedplate 40 and a flow stabilizing filter 50 are placed in a path throughwhich the coolant flows to each inner tub 20. Therefore, the coolant,finally discharged from the inner tubs 20 through discharging holes 21,flows in a very stable flow pattern.

However, the conventional laminar flow-type coolant header having theabove-mentioned construction is problematic in that, because the headerhas only two rows of discharging holes 21 in a single outer tub 10, theheader may not discharge a large amount of coolant onto a hot rolledstrip at one time, thus failing to provide a high cooling rate.Therefore, to quickly cool a hot rolled strip having a high temperatureusing the conventional laminar flow-type coolant headers, a great numberof coolant headers must be coupled together in series, thus enlargingthe size of a hot rolled strip cooling device and increasing theinstallation costs of the device.

[Technical Problem]

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a coolant header for hot rolled strip coolingdevices, which has several rows of discharging holes formed in a singlebody, thus discharging coolant in a relatively stabilized laminar flowpattern and quickly cooling hot rolled strips.

[Technical Solution]

According to an embodiment, the present invention provides a coolantheader for hot rolled strip cooling devices, which cools a hot rolledstrip fed from a finish rolling mill, comprising: a body provided with aplurality of discharging holes formed through the lower surface of thebody such that the discharging holes are arranged along the width of thehot rolled strip and at least three rows of discharging holes arearranged along the length of the hot rolled strip; a coolant pipeprovided in the coolant header, with an outlet hole formed on a sidesurface of the coolant pipe to discharge coolant; an inclined plateplaced in front of the outlet hole of the coolant pipe such that theplate is inclined downwards, thus evenly distributing the coolantdischarged from the outlet hole over the entire surface of the coolantheader; a perforated plate placed above the discharging holes andcausing the coolant to flow uniformly; and a flow stabilizing filterplaced between the discharging holes and the perforated plate andcausing the coolant to flow in a stabilized laminar manner.

[Advantageous Effects]

The present invention discharges laminar flow coolant in multiple rows,thus quickly cooling a hot rolled strip having a high temperature andmore efficiently controlling the temperature of the hot rolled stripwhile controlling the strip.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a conventional laminar flow-type coolant header;

FIG. 2 illustrates the schematic construction of a coolant header forhot rolled strip cooling devices according to an embodiment of thepresent invention;

FIG. 3 illustrates the sectional area of a flow stabilizing filter ofFIG. 2 in an enlarged view; and

FIG. 4 illustrates the sectional area of a discharging hole of FIG. 2 inan enlarged view.

MODE FOR INVENTION

Hereinbelow, a preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 illustrates the schematic construction of a coolant header forhot rolled strip cooling devices according to an embodiment of thepresent invention.

FIG. 3 illustrates the sectional area of a flow stabilizing filter ofFIG. 2 in an enlarged view; and

FIG. 4 illustrates the sectional area of a discharging hole of FIG. 2 inan enlarged view.

As shown in FIG. 2, the coolant header according to the presentinvention comprises a body 100, two coolant pipes 120, two inclinedplates 130, a perforated plate 140, and a flow stabilizing filter 150.

The body 100 has a longitudinal tub structure having a tetragonalcross-section and is arranged along the width of the strip (in thevertical direction in the drawings). The lower surface of the body 100is provided with a plurality of discharging holes 110 to dischargecoolant. In the present invention, the discharging holes 110 arearranged along the length and width of the hot rolled strip such thatthe holes 110 are spaced apart from each other at regular intervals,thus a great quantity of coolant may be evenly discharged from theheader onto the strip. Particularly, several rows of discharging holes110 are arranged along the length of the hot rolled strip, so that agreat amount of coolant may be discharged onto the strip. It ispreferred to set the intervals between the discharging holes 110 to 20mm to 30 mm. The above-mentioned intervals prevent the streams ofcoolant discharged from the holes 110 from interfering with each other.Furthermore, if the diameter of the discharging holes 110 is smallerthan 3 mm, the coolant discharged from the holes 110 may be easilyunstabilized. Thus, it is preferred to set the diameters of thedischarging holes 110 at 5 mm to 10 mm.

The coolant pipes 120 are placed in the upper part of the body 100 andsupply coolant from a coolant tank to the body 100. Each of the coolantpipes 120 is provided with an outlet hole 121 on a side surface thereof.To discharge the coolant upwards, the outlet hole 121 is formed on anupper part of the side surface of the coolant pipe 120. It is preferredto form the outlet holes 121 on respective pipes 120 at positions whichare at angles ranging from 0 to 30 degrees above a horizontal axispassing through the centers of the two coolant pipes 120.

The inclined plates 130 are placed in front of the respective outletholes 121 of the coolant pipes. Each of the plates 130 is inclineddownwards, thus guiding the coolant discharged from the outlet hole 121onto the lower surface of the body 100. Therefore, the coolantdischarged from the outlet holes 121 collides with the inclined plates130 and is scattered into several streams, thus being evenly distributedover the entire surface of the perforated plate 140. In the above state,to maximize the coolant distribution efficiency, it is preferred to makethe surfaces of the inclined plates 130 uneven. In the preferredembodiment, the coolant pipes 120 are arranged along the width of thehot rolled strip. However, it should be understood that the coolantpipes may be arranged along the length of the hot rolled strip whennecessary.

The perforated plate 140 having a great number of perforations is placedbelow both the coolant pipes 120 and the inclined plates 130. Theperforated plate 140 is placed parallel to the lower surface of the body100, so that the plate 140 secondarily distributes the coolant flowingfrom the inclined plates 130 and primarily reduces the velocity of theflowing coolant.

The flow stabilizing filter 150 is placed between the discharging holes110 and the perforated plate 140.

As shown in FIG. 3, the flow stabilizing filter 150 comprises a pipestructure comprising a plurality of pipes having a polygonalcross-section arranged in parallel with each other, and a porous pad 155placed on the upper end of the pipe structure. The cross-section of theplurality of pipes may be a tetragonal, pentagonal or hexagonalcross-section. The pipes 151 of the pipe structure may be arrangedlongitudinally and latitudinally over the entire surface area of thecoolant header 100, thus having a predetermined lattice structure. Theupper end of each pipe 151 is completely open, while the lower end ofthe pipe 151 is partially open, so that the sectional area of the openupper end thereof is larger than the sectional area of the open lowerend. Thus, the flowing velocity of the coolant, which passes through thetetragonal pipes 151, is reduced, thereby becoming laminar due to thedifference of the sectional area between the upper and lower ends of thepipes 151. If each of the pipes 151 is long, the flow of coolant mayform vortices while the coolant flows along the long pipes 151. Thus,vortex prevention plates 152 may be installed in each of the pipes 151as shown in FIG. 3.

A porous pad 155 is provided at the upper end of each of the pipes 151.The porous pad 155 may contain therein a predetermined quantity ofcoolant, as expected of a sponge, and causes the coolant to beintroduced into the pipes 151 Furthermore, the porous pad 155 causes thecoolant to flow in a horizontal direction due to capillary action of theporous pad 155 comprising a fine fibrous tissue. In other words, theporous pad 155 acts as a buffer which reduces the flow velocity of thecoolant dropping from the perforated plate 140 and promotes uniformhorizontal distribution of the coolant.

Therefore, the coolant, which sequentially passes through the perforatedplate 140, porous pads 155 and pipes 151, becomes essentially uniformalong a horizontal surface of the body 100, and, furthermore, thedropping velocity of the coolant is substantially reduced. Thus, whenthe coolant is discharged from the discharging holes 110 of the body100, the flow of coolant becomes stabilized and laminar.

The lower surface of the body 100 is formed by a plate havingpredetermined thickness. Each of the discharging holes 110, formedthrough the plate of the lower surface of the body, is shaped as anozzle which is tapered downwards as shown in FIG. 4. The tapereddischarging holes 110 may increase the flow velocity of the coolant,which has been reduced to a low level through several stabilizing steps,to a desired level.

Generally, the coolant, discharged from a laminar flow-type coolantheader, flows at a very low velocity, so that the streams of the coolantbecome thinner as the streams are spaced farther from the coolantheader. Thus, the sectional area of the coolant, which actually coolsthe surface of a hot rolled strip, becomes reduced. In consideration ofthis problem, the present invention changes the arrangement of thedischarging holes 110 to the above-mentioned structure. Thus, thepresent invention is advantageous in that the present inventionmaintains the streams of the coolant, discharged onto the surface of ahot rolled strip, constant, thereby increasing in practice the sectionalarea of the coolant which collides with the strip. Furthermore, theangle of each tapered discharging hole 110 of the present invention maybe changed according to the distance between the body 100 and a hotrolled strip to be cooled. It is preferred to set the angle θ of thetapered discharging hole 110 to 90 to 120 degrees.

INDUSTRIAL APPLICABILITY

Although a coolant header for hot rolled strip cooling devices accordingto the preferred embodiment of the present invention has been disclosedin conjunction with the accompanying drawings for illustrative purposes,those skilled in the art will appreciate that various modifications,additions and substitutions are possible, without departing from thescope and spirit of the invention as disclosed in the accompanyingclaims.

1. A coolant header for hot rolled strip cooling devices, which cools ahot rolled strip fed from a finish rolling mill, comprising: a bodyprovided with a plurality of discharging holes arranged along the lengthand width of the hot rolled strip; a coolant pipe provided in thecoolant header, with an outlet hole formed on a side surface of thecoolant pipe to discharge coolant; an inclined plate placed in front ofthe outlet hole of the coolant pipe such that the plate is inclineddownwards, thus evenly distributing the coolant discharged from theoutlet hole over an entire surface of the coolant header; a perforatedplate placed above the discharging holes and causing the coolant to flowuniformly; and a flow stabilizing filter placed between the dischargingholes and the perforated plate and causing the coolant to flow in astabilized laminar manner.
 2. The coolant header for hot rolled stripcooling devices according to claim 1, wherein both the coolant pipe andthe inclined plate are placed along the width of the body.
 3. Thecoolant header for hot rolled strip cooling devices according to claim1, wherein the flow stabilizing filter comprises: a pipe structurecomprising a plurality of pipes having a polygonal cross-sectionarranged in parallel with each other; and a porous pad placed on anupper end of the pipe structure, which stabilize the flow of coolant. 4.The coolant header for hot rolled strip cooling devices according toclaim 3, wherein the cross-section of the plurality of pipes is selectedfrom the group consisting of tetragonal, pentagonal and hexagonalcross-sections.
 5. The coolant header for hot rolled strip coolingdevices according to claim 3, wherein each of the plurality of pipes isconfigured such that a sectional area of an open upper end thereof islarger than a sectional area of an open lower end, and furthercomprises: a vortex prevention plate connected both to the open upperend and to the open lower end, and guiding the laminarly flowingcoolant.
 6. The coolant header for hot rolled strip cooling devicesaccording to claim 1, wherein the inclined plate has an uneven surfaceto evenly distribute the coolant discharged from the outlet hole ontothe perforated plate.
 7. The coolant header for hot rolled strip coolingdevices according to claim 1, wherein the outlet hole is formed at aposition which is at an angle ranging from 0 to 30 degrees above ahorizontal axis passing through a center of the coolant pipe, so thatthe coolant is discharged upwards through the outlet hole.
 8. Thecoolant header for hot rolled strip cooling devices according to claim1, wherein the discharging holes have diameters from 5 mm to 10 mm. 9.The coolant header for hot rolled strip cooling devices according toclaim 1, wherein the discharging holes are spaced apart from each otherat intervals from 20 mm to 30 mm.
 10. The coolant header for hot rolledstrip cooling device according to claim 1, wherein each of thedischarging holes is defined by a tapered surface to gradually reduce adiameter of the discharging hole in a direction moving towards the hotrolled strip.
 11. The coolant header for hot rolled strip coolingdevices according to claim 10, wherein an angle of the tapered surfaceof each of the discharging holes is 90 to 120 degrees.
 12. The coolantheader for hot rolled strip cooling devices according to claim 2,wherein each of the discharging holes is defined by a tapered surface togradually reduce a diameter of the discharging hole in a directionmoving towards the hot rolled strip.
 13. The coolant header for hotrolled strip cooling devices according to claim 3, wherein each of thedischarging holes is defined by a tapered surface to gradually reduce adiameter of the discharging hole in a direction moving towards the hotrolled strip.
 14. The coolant header for hot rolled strip coolingdevices according to claim 4, wherein each of the discharging holes isdefined by a tapered surface to gradually reduce a diameter of thedischarging hole in a direction moving towards the hot rolled strip. 15.The coolant header for hot rolled strip cooling devices according toclaim 5, wherein each of the discharging holes is defined by a taperedsurface to gradually reduce a diameter of the discharging hole in adirection moving towards the hot rolled strip.
 16. The coolant headerfor hot rolled strip cooling devices according to claim 6, wherein eachof the discharging holes is defined by a tapered surface to graduallyreduce a diameter of the discharging hole in a direction moving towardsthe hot rolled strip.
 17. The coolant header for hot rolled stripcooling devices according to claim 7, wherein each of the dischargingholes is defined by a tapered surface to gradually reduce a diameter ofthe discharging hole in a direction moving towards the hot rolled strip.18. The coolant header for hot rolled strip cooling devices according toclaim 8, wherein each of the discharging holes is defined by a taperedsurface to gradually reduce a diameter of the discharging hole in adirection moving towards the hot rolled strip.
 19. The coolant headerfor hot rolled strip cooling devices according to claim 9, wherein eachof the discharging holes is defined by a tapered surface to graduallyreduce a diameter of the discharging hole in a direction moving towardsthe hot rolled strip.
 20. The coolant header for hot rolled stripcooling devices according to claim 12, wherein an angle of the taperedsurface of each of the discharging holes is 90 to 120 degrees.
 21. Thecoolant header for hot rolled strip cooling devices according to claim13, wherein an angle of the tapered surface of each of the dischargingholes is 90 to 120 degrees.
 22. The coolant header for hot rolled stripcooling devices according to claim 14, wherein an angle of the taperedsurface of each of the discharging holes is 90 to 120 degrees.
 23. Thecoolant header for hot rolled strip cooling devices according to claim15, wherein an angle of the tapered surface of each of the dischargingholes is 90 to 120 degrees.
 24. The coolant header for hot rolled stripcooling devices according to claim 16, wherein an angle of the taperedsurface of each of the discharging holes is 90 to 120 degrees.
 25. Thecoolant header for hot rolled strip cooling devices according to claim17, wherein an angle of the tapered surface of each of the dischargingholes is 90 to 120 degrees.
 26. The coolant header for hot rolled stripcooling devices according to claim 18, wherein an angle of the taperedsurface of each of the discharging holes is 90 to 120 degrees.
 27. Thecoolant header for hot rolled strip cooling devices according to claim19, wherein an angle of the tapered surface of each of the dischargingholes is 90 to 120 degrees.